mlxsw: spectrum: Don't count on FID being present

Not all vPorts will have FIDs assigned to them, so make sure functions
first test for FID presence.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index ea007f0..0c42515 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -3323,7 +3323,9 @@
 
 	list_for_each_entry(mlxsw_sp_vport, &mlxsw_sp_port->vports_list,
 			    vport.list) {
-		if (mlxsw_sp_vport_br_get(mlxsw_sp_vport) == br_dev)
+		struct net_device *dev = mlxsw_sp_vport_br_get(mlxsw_sp_vport);
+
+		if (dev && dev == br_dev)
 			return false;
 	}